1. Field of the Invention
The present invention relates to a gas supply apparatus and method, and more particularly, to a gas supply apparatus and method capable of efficiently supplying a liquefied gas filled into a gas container in a stable state by vaporizing the liquefied gas within the gas container.
2. Background Art
Gas such as WF6, ClF3, BCl3 and SiH2Cl2 used in the field of semiconductor production and so forth are filled and stored in gas containers in a liquid state at normal temperature (liquefied gas state), and when these gases are used, the gas container is heated from the outside as necessary to promote vaporization of the liquefied gas within the gas container.
In addition, in the supplying of such gases, although it is necessary to maintain the pressure of supplied gas led out from the gas container at a roughly constant pressure close to a set pressure, in the past, the pressure inside the gas container or the pressure of a gas supply line connected to it was measured, and the amount of heating of the gas container was regulated based on that change in pressure. However, in the case of controlling the pressure using only this type of pressure feedback, due to the low responsiveness, there are times when it becomes difficult to attain stable control in cases of large fluctuations in the amount of gas supplied, and, in particular, during the initial supply of gas when the pressure inside the gas container is low, there was the problem of a long period of time being required until the pressure stabilized. Moreover, in the case of supplying gas from a gas container, it is also necessary to reliably determine the time when the gas container is to be replaced by detecting the residual amount of gas in the gas container.
The object of the present invention is to provide a gas supply apparatus and method, which together with being able to efficiently heat or cool a gas container from the outside, is able to maintain the pressure of supplied gas roughly constant, while also being able to reliably detect the residual amount of gas in the gas container.